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No dangerous changes seen in Hong Kong H9N2 virus

Jan 7, 2009 (CIDRAP News) – Hong Kong health officials reported today that the H9N2 avian influenza virus that recently infected a 2-month-old girl from mainland China has not acquired any genes from human-adapted flu viruses, implying that it is unlikely to pose a major danger to humans.

In a news release, the Centre for Health Protection (CHP) in Hong Kong's Department of Health said genetic sequencing has shown that all the virus's genes are of avian origin.

"DNA sequences of the genes concerned show that they are of avian origin, and reassortment with genes of human influenza origin has not been found," an anonymous CHP spokesman said in the release.

"The epidemiological and genetic findings so far suggest that the H9N2 virus has shown no signs of increased risk for human-to-human transmission," he said.

The spokesman said the virus is very similar to an H9N2 virus isolated from a 9-month-old girl in Hong Kong in 2007. He added that the virus has been found to be sensitive to the antiviral drugs oseltamivir and amantadine.

H9N2 viruses are distinct from the deadly Asian strain of H5N1 but are regarded as having the potential to evolve into a pandemic strain. The current case is the fifth H9N2 infection reported in Hong Kong since 1999, all of them in infants and young children who had mild illnesses and recovered.

The 2-month-old girl, from Shenzhen in southern China, is still being treated in Hong Kong's Tuen Mun Hospital for another disease, the CHP said. The H9N2 virus was not found in nasopharyngeal samples taken from the girl on Jan 2, the statement said.

In other developments, the World Health Organization (WHO) today recognized two human H5N1 cases reported by Asian governments yesterday, one in China and one in Vietnam.

The Chinese case involved a 19-year-old woman from Beijing who fell ill Dec 24 and died Jan 5, the WHO said in a statement. China has had 31 H5N1 cases, 21 of them fatal.

The patient in Vietnam is an 8-year-old girl from Thanh Hoa province who became ill Dec 27 and is in stable condition, the WHO confirmed. Vietnam has had 107 H5N1 cases with 52 deaths.

Echoing earlier reports, the WHO said both patients had had contact with poultry before they got sick.

The two cases raised the WHO's global H5N1 count to 393 cases with 248 deaths. The agency classified the two illnesses as 2008 cases, raising the total for the year to 42 cases with 31 deaths. That represents a case-fatality rate of 74%.

Vietnam's agriculture ministry has confirmed an H5N1 outbreak among poultry in Thanh Hoa province, the home of the sick 8-year-old, according to a Reuters report published today.

About 400 chickens in Ba Thuoc district, where the girl lives, died of the disease, the report said. District authorities in Ba Thuoc, about 94 miles south of Hanoi, have slaughtered nearly 8,000 chickens in efforts to stop the outbreak, Reuters reported.

Thanh Hoa is the second province in 2 weeks to report an H5N1 outbreak in poultry, having been preceded by Thai Nguyen, north of Hanoi, the story said.